Handicap | EPFL Graph Search

Le handicap est la limitation des possibilités d'interaction d'un individu avec son environnement, menant à des difficultés psychologiques, intellectuelles, sociales ou physiques. Le handicap est d'abord pensé comme relatif à une déficience provoquant une incapacité puis il est redéfini relativement à une inégalité de moyens, en intégrant l'idée que « des interventions destinées à lever les obstacles environnementaux et sociaux sont nécessaires ». Le terme de « handicap » a ainsi acquis en plus du médical une dimension sociale, et il renvoie aux difficultés de la personne dite « en situation de handicap » face à un environnement donné en matière d'accessibilité, d'expression, de compréhension ou d'appréhension. Le niveau de handicap, c'est-à-dire l'ampleur des limitations d'activité et de participation, est ainsi variable en fonction des contextes (sociétaux, humains, techniques, juridiques). Le handicap affecte de personnes en Europe et dans le mon

The Impact of Sharing Markets on Product Durability

Maryam Razeghian Jahromi, Thomas Alois Weber

This paper studies the effects of sharing markets on the prices for new products and on product design in terms of durability. In a dynamic economy with overlapping generations, consumers take strategic purchasing decisions, anticipated by a durable-goods monopolist. Without sharing, the optimal durability increases in the production cost. In the presence of sharing, a producer prefers to limit durability for low-cost products, effectively disabling a secondary sharing market. However, all else equal, a peer-to-peer economy never decreases the incentives to provide durability.

2016

Strategic Durability with Sharing Markets

Maryam Razeghian Jahromi, Thomas Alois Weber

Electronic sharing markets are contributing to a paradigm shift, from consuming products to accessing products. This paper studies the effects of sharing markets on the prices for new products and on product design in terms of durability. In a dynamic economy with overlapping generations, consumers take strategic purchasing decisions, anticipated by a durable-goods monopolist. Without sharing, the optimal durability increases in the production cost. For low-cost products, a producer prefers to limit durability, effectively disabling a secondary sharing market. The presence of sharing never decreases the incentives to provide durability thus contributing to sustainable product design.

2019

Program Analysis and Compilation Techniques for Speeding up Transactional Database Workloads

Mohammad Dashti Rahmat Abadi

There is a trend towards increased specialization of data management software for performance reasons. The improved performance not only leads to a more efficient usage of the underlying hardware and cuts the operation costs of the system, but also is a game-changing competitive advantage for many emerging application domains such as high-frequency algorithmic trading, clickstream analysis, infrastructure monitoring, fraud detection, and online advertising to name a few. In this thesis, we study the automatic specialization and optimization of database application programs -- sequences of queries and updates, augmented with control flow constructs as they appear in database scripts, user-defined functions (UDFs), transactional workloads and triggers in languages such as PL/SQL. We propose to build online transaction processing (OLTP) systems around a modern compiler infrastructure. We show how to build an optimizing compiler for transaction programs using generative programming and state-of-the-art compiler technology, and present techniques for aggressive code inlining, fusion, deforestation, and data structure specialization in the domain of relational transaction programs. We also identify and explore the key optimizations that can be applied in this domain. In addition, we study the advantage of using program dependency analysis and restructuring to enable the concurrency control algorithms to achieve higher performance. Traditionally, optimistic concurrency control algorithms, such as optimistic Multi-Version Concurrency Control (MVCC), avoid blocking concurrent transactions at the cost of having a validation phase. Upon failure in the validation phase, the transaction is usually aborted and restarted from scratch. The "abort and restart" approach becomes a performance bottleneck for use cases with high contention objects or long running transactions. In addition, restarting from scratch creates a negative feedback loop in the system, because the system incurs additional overhead that may create even more conflicts. However, using the dependency information inside the transaction programs, we propose a novel transaction repair approach for in-memory databases. This low overhead approach summarizes the transaction programs in the form of a dependency graph. The dependency graph also contains the constructs used in the validation phase of the MVCC algorithm. Then, when encountering conflicts among transactions, our mechanism quickly detects the conflict locations in the program and partially re-executes the conflicting transactions. This approach maximizes the reuse of the computations done in the first execution round and increases the transaction processing throughput. We evaluate the proposed ideas and techniques in the thesis on some popular benchmarks such as TPC-C and modified versions of TPC-H and TPC-E, as well as other micro-benchmarks. We show that applying these techniques leads to 2x-100x performance improvement in many use cases. Besides, by selectively disabling some of the optimizations in the compiler, we derive a clinical and precise way of obtaining insight into their individual performance contributions.

EPFL2017

Program Analysis and Compilation Techniques for Speeding up Transactional Database Workloads

Mohammad Dashti Rahmat Abadi

EPFL2017